Controlling alternating-current motors.



PATENTED JULY 23, 1907.

mssme s,

E. STEINMETZ. G ALT HEATING GURRENT MOTORS.- APPLICATION FILED JAN. 25, 1904.

CONISRGLL'EN 3 SHEETS-SHEET 1.

\nvefibor? Charies P. Steinmetz M PATENTED JULY 28 P. smmmz.

CONTROLLING ALTER-NATING CURRENT MOTORS.

APPLICATION TILED JAN.25,190-1.

3 SHEETSSHEET 3.

L w t M m N Nul wv. E C

UNITED STATES PATENT CHARLES P. STEINMETZ, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

CONTRQLLING ALTERNA'IING-CURRENT Specifieationof Letters Patent. I

Psitented July 23, 1807.

Application filed JanuaryZB, 190-1:- Seriel No. 190,437.

To all whom it may concern:

Be it known that 1, CHARLES PI Srsmrrnrz, a citizen I 'of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented ceri tain newand useful Improvements in Controlling Alternating-Current Motors, of which the following is a specification.

My invention relates to the'control of alternatingcurrent motors of the type known as repulsion motors, and comprises both a novel method of control and a novel system by means of which the said method may be carried into effect.

Ithas heretofore been proposed to control repulsion motors both as regards speed and torque by varying the relative angular displacement between the lineoi the prim ary field and the line of the short-oi rcuiting brushes on the secondarymember, and although this method may be utilized for controlling the speed and torque of a repulsion motor over any desired range, it is open to the objection that the sparking at the brushes at starting is considerably increased when the angle of shift between the primary field and the short-ciicu'rting brushes is large. The method constituting my present invention involves the combination with the method of con trol above referred to of a control of the potential at the motor terminals.

By the control constituting my present invention, 1

am enabled to extend the range of speed and torque variation beyond that which can be obtained by shift ing the commutator brushes or the line of magnetization of the, primary member, while at the same time retaining all the advantages incident to this latter method 01' control. 1

My inyention will be better understood by reference to the following description taken inconnection with the accompanying drawings, in which Figures 1 to 4 inclusive are diagrams illustrating one way of practicing my invention; Fig. 5 is a diagram of a complete system of control arranged to carry my inven- 40 tion into 'efiect, the said system being adapted for the control of the motors on a car or train; Fig. 6 shows a form of brush-shifting mechanism adaptedto my: invention; Fig. 8 shows a detail of 'the brush-shitting mechanism and Fig. 7 is an explanatory diagram.

In the particular embodiment of myinvention which I have illustrated in my present application, the mo tors are arranged to be connected for starting in a series -roup or groupswith the short-circuiting commutator brushes on the secondary members displaced by a maxim'um angle from-the line of the primary held. To in- "crease .the speed of the motors the short-circuiting brushes are arranged tobe' shifted step by step until they lie along a line displaced in the neighborhood of 15 from the line of the primary field. -The motor connections are then changed from series to multiple grouping and at the same time the commutator brushes are returned to the position of maximum angular displacement, and finally the commutator brushes are moved step by step, as before, until they are brought to the position in which the greatest torque per volt ampere is 69 obtained, this position depending somewhat upon the design of the motor, but being in general in the neighborhood of 15 from the line of the primary field.

Referring to Figs. 1 to 4'inclusive which illustrate. diagrammatically the motor control above described, M M represent two repulsion motors having their primary windings connected in series between trolley and ground. In Fig. 1 the shorL-circuiting brushes oi the secondary member are shown positioned along the line ac. This is the starting position. in order to increase 79 the speed ol'the motors the short circuiting brushes are gradually shifted until they lie along the line bl). This arrangement is shown in Fig. 2 of the drawings and corresponds to the full-series position in the ordinary seriesparallel control oi direct-current motors. .ln order to obtain a still higher speed the connections of the motors are shifted from series to parallel, the commutator brushes at the same time being returned to the position of rararriinum angular displacement. The connections ior this position are indicated in Fig. 3 of the drawing 80 and correspond to the first multiple position in the ordinary series-parallel control of dircctcurrcnt motors.

To increase the speed still further the short-circuiting brushes are again shifted from their position along the line an to a position along the line bb, as shown in Fig. 35 4, the connections illustrated in this diagram corresponding to the full-multiple position of the ordinary series-parallel control of direct-current motors.

Since my, invention is especially applicable to the control of motors driving railway cars or trains, J. have illustrated the preferred embodiment a complete control system suitable for application to a single car or to one of the cars of train which is to be operated from a master-controller located at any desired point. In illustrating thisembodiment of my invention 1 have shown only I a pair of motors connected with their switches in a single worl: circuit, with the controlling devices for the motors snd'switches connected to a. system of conductors to which is also connected at single master-controller. It will be understood that the 'ircuits for a single car are here shown, and that the system of conductors may be extendedto any length and that the controlling devices for any number of groups of motors, as well as any number of master-conlrollers, may be connected thereto. Terminal connections are indicated at each end of the system of conductors, and, as train-control systems are well known in the art, it is not necessary to illustrate the circuits for the other cars,

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ders' and reversing switches are w iown to the art, and any well known form oi interlocl' m be used. i and U represent diagramn'iatically the brush-sh "'ing mechanism for the motors M and M? respectively, & which are controlled by the coils t, 12 etc. This constationary contacts o, etc, and assume the com 1.5 cylinder Ito be moved so that the contact flngersir, 1:

etc. are in engagement with the movahie contacts on the line IX: two different circuits are now closed across the transformer secondary C the current passing from the upper end of transformer secondary C divides; one circuit passes to the stationary contact 7;", to contact segments j to contact is, through coil. S of switch B,

through contacts .9 s to contact in, to contact segments j, to contact is, and back to the leit-iiand side oi 1, ans

former secondary G. Coil S is" the operating "ii for seriesparallel switch 3 to throw it into the sent position. Coil P is the controlling coil for the no switch to throw it into the parallel position. rims by the passage of current through coil 3, switch B is thrown into the series position, with contact-lingers l) and b in -Contact with segment :1; b and s in contact witlrd' and d in contact with b and b.

The second circuit from.transformer secondary 1' cs to contact finger o, to segment n, to contact 0 to coil F of switch H, to contactifinger If, to segment j",

to contact finger k and transformer secondary C Coils F and R are the controlling coils [or the reversing switch 11, throwing either set of movable contacts into engagement with the stationary contact ting Thus the second control circuit connects the motors for 40 theirforward direction of rotation. The motors are now connected in series position and the hold coils are connected for forward rotation, but the main switch A is as yet open and no current passes through the working circuit. If now controlling switch .l he moved to the SCC" end position 2X, an additional circuit will be closed.

Current now passes from the right-hand end of trans former secondary 0 through contact-finger k", to segment j to contact-finger k, to contact 12, to contact d to contact b to coil 11 of switch Ate contactfin or k to contact se ment to contact-fin er r J l; 3

to transformer secondary 0 This circuit is closed through coil a. 'Coii a is the operating coil for main switch A and raises the switch-har into engagement with its contacts, closing the work circuit. 1 he switch-- bar is arranged to engage contacts 8 s and p p when it is in its lower position. Thus when switch A is raised to close the Working circuit, the circuits of coils S and P are open at contacts sand p. Thus any I change from series position of seriesparsllel switch ii is prevented as long as main switch A is closed. 'lhus main switch A and series-parallel switch B are inter locked. Switch A cannot be closed until switch .8 is moved into either the series or parallel position so that contacts I) and b engage contacts (Z or (i and on the other hand switch B cannot be moved except when circui under load. It will further be notice-:1 that the re e EV-fiikli H is never called upon to open the work c: (.uit under load, since it can be moved only when main reversing switch N is operated, and switch is mechanically interlocked with main-controlling switch l, so that it cannot be operated except when con trol switch is in the off position, and consequently main swifch r1 open.

Rciu .113; to the consideration of the circuits, the connections for the second position of switch .l have lieen described. The working circuit is closed and the motors start at their lowest speed or series position. for the brushes are displaced to the starting position. ii now switch I is moved to the position 23X, only one change occurs. A new circuit is now (sllllllished as follows: from the upper end of transformer secondary (1 to contact k to segmeuh'i to contact ls", t o to contact 11., to contact 0, through the two coils e in parallel to contact 13 to segment 3'. to contact ls, to transformer secondary Thus by the rgizing of coils r the brushes are moved one slop nearer to their running position, and the speed of the rotor is increased. As switch If is moved to positions 4X and 5X, the circuit is closed through coils w and n" rcs 'u-ctivcly, and when switch .l is on the position 5X the motors are operating at their maximum speed for series connection. ll non/ the switch I is moved to the pos ion 5X", thecircuit is broken lhroughr-oil acontrolling the'main switch and through coils v, w, etc. Main switch A thus falls and opens the work circuit, while brush-shifting mechanisms U, ll etc. are returned hy their springs to the starting position, as will l)('- hereinafter described. By the opening oi; main switch A the circuits of coils S and P are again closed at contacts 3 and Now as switch If is moved to position (3X, the circuit through (oil I? is closed by means of contact-finger is and segment Series-parallel switch B is accordingly moved to the parallel position. In moving switch .l to position 7X main switch A is again closed, closing the work circuit and opening the circuit of control coil l in passing through the re ifitlllllllg positions of switch 5, coils r, "1Y etc. will again he serially energized and the motors will he brought to lull speed for the parallelconnections.

it is evident that any number of main switches, scrics-parallel switches and ln'ush-shil'ting coils may be controlled by one control switch I, all the main switches being electrically interlocked with the scrics parallcl switches as has been already described. Furthermore any number of reversing switches H may he controlled by the main reversing switch N mechanically interlocked with the maiiicontrol switch '.T.

It remains only to describe the mechanism by which the step-by-step shifting oi the brushes is obtained. This mecl'ianism is illustrated in Figs. 6 and 8. l() l0 represent the briisl'ics bearing on the commutator 1]. and carried by the ring 12, which is mounted so as to be capable of rotation around the commutator 11 in the ordinary manner ei' bruslnholders. The support, which 100 said h:- when muralfor ihplacc stance from .it to A shifting devices, has and said devices 01 sysnd a muster-( m controlomprismff :hililng nix motors,

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17. The method or" controlling a plurality of repulsion motors. which r-onsists in Wirying the displacement of the brushes of the motors from the line of field magnetization and varying the serie pnrullnl relt tions of said motors.

18. The method r r-ontrollii-ig :t plurality of repulsion motors. which con ts in connecting the motors in series to u source of current with the brushes of the motors (lisplucetl at maximum distant-e from the line of field mugnetr zalion, then shifting the luushes toward the line of ma netizution, then lifipltlClD): the hrushes and connecting the motors in parallel, and then shifting: the brushes toward the line of magnetization.

1.). The method of controlling, a plurality of motors, which consists in rlisplueing the brushes: from running pesition and connecting the motors in ser .5 to the source 01 enrrent. then shitting: the brushes to running pos' then displacing the brushes and connecting the motors in pnrulh-l. and then shifting the brushes to running position.

1:0. The method of controlling the operation of repulsion motors. which eonsists in varying the angular displacement, hetw en the line of the primary held and the line of the shert-ciruuiting brushes to vary the speed and torque of the motor within certain limits, and varying the potentlal at the motor terminals to increase the range of control.

21. The method of controlling the operation of repulsion l motors, which (10 is in applying varying potentials to l the motor terminals and for ouch potential applied varying i the spa-ed and torque of the motors by trying the ungulnr displacement hetween the priuntry field and the line of the short-circuiting brushes. I 22. The method of controlling the operation of repulsion motors, w 11 const s in starting tln sumo with the com mututor brushes displaced by :1 maximum angle from the line of the primury field and with :2 minimum potential im pre, (l on the motor terminuis. then gradually reducine the shift of the liruehes. then returning illtl hrushes to the llltlhlllllllli angle and increasing the poteniiul 21 the motor I. ninnls. and linull again e-rnduully rerlueing the shift. ot the bru hes.

4 In witness whereof I have her unto set A) 22ml (lay of lqnunry, i901. l

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